The two root causes behind what the reviews of the wait found, both in
the code as it stands. Each with a check that failed first.
EMIT stored its character and only then looked whether the buffer was
exactly full. A flush that ended in a fault -- the stack too deep to
begin a message -- left the buffer full, and the fault's own message was
then put past its end, with (OUT^) never again at the end to be flushed.
The 28 cells after the buffer happen to be unused, so nothing showed;
the wait had put the ports there, and the node blocked writing to one.
EMIT now sends a buffer it finds full before it stores.
AWAIT, and (GATE) when a neighbour is writing, read a message's first
word and then used stack that was not known to be there. With 27 or 28
values on the stack, or 28 or 29 calls deep, a line typed during AWAIT
was taken and never answered. (ROOM) tries six cells and four return
entries first: if they are not there the text ends 'Stack overflow' with
nothing read. (GATE) tries the three cells its writing needs before a
first word goes; it was safe before only by the order things were done.
v4/tools/depthsweep.py runs every message path of the hosted product at
every depth of both stacks: each line typed must be answered and the
node must come back. hosted-check runs it.
make -C v4 test and sanitize at both widths, hosted-check.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
